Interesting Gary! I have used high pressure fuel injection hose from my motor factor. I does not smell at all. I have also done plenty of customer cars in it to.
If you want to be flash you can use Krontec stuff, its 8mm or 10mm ali tube and get dash fitting for the ends. It works out as a mid price option.
Simon.
it dont bother me that much tbh once driving you dont notice it, its just if its left for a day or so you get a wiff when you open the door i ve learned to accept its just the hose used i was contemplting running the pipes back under neath the car and using 10mm copper pipe that only leaves a small amount of pipe in the boot area then